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17 Degree Capacity Goes South When HSPF Goes North

Anyone understand why? If you peruse the aridirectory.org HP database you
can't help notice that the ARI 17 degree values move inversly to the HSPF
figure of merit. It looks like ECM fans and oversize coils are used to jack up
both SEER and HSPF so could it be the case that the oversize coils drop in
efficiency faster as the outdoor temp drops?

Got a link to that site showing this data? In my experience the two stage high HSPF units do pretty well at low temps. The inverter minisplits do REALLY well at low temps!

Originally Posted by hivacjack

Anyone understand why? If you peruse the aridirectory.org HP database you
can't help notice that the ARI 17 degree values move inversly to the HSPF
figure of merit. It looks like ECM fans and oversize coils are used to jack up
both SEER and HSPF so could it be the case that the oversize coils drop in
efficiency faster as the outdoor temp drops?

Anyone understand why? If you peruse the aridirectory.org HP database you
can't help notice that the ARI 17 degree values move inversly to the HSPF
figure of merit. It looks like ECM fans and oversize coils are used to jack up
both SEER and HSPF so could it be the case that the oversize coils drop in
efficiency faster as the outdoor temp drops?

What's wrong with a 4-ton 2-stage HP rated at 9.75 HSPF and 34K BTU at 17*.

What's wrong with a 4-ton 2-stage HP rated at 9.75 HSPF and 34K BTU at 17*.

stay within the same capacity to make the comparison. i.e. compare 3Ton single stage
to 3Ton single stage. There aren't many 2 stage HP's which have a lower HSPF version
in the product line. For example compare the ssz14 goodman's with the ssz16 goodman's.